Flying magnetic head slider for a magnetic disk drive

ABSTRACT

A magnetic head slider of the present invention includes a generally C-shaped leading rail extending from the leading edge of an air bearing surface and concave toward the trailing edge of the same. A pair of trailing rails extend from substantially the center of the concavity of “C” of the leading rail and flared away from each other toward the trailing edge. The trailing rails are spaced by a preselected distance from each other in the vicinity of the concavity of the trailing rail, then extend toward the trailing edge while bending away from each other, and then respectively extend toward the right and left ends of the trailing edge while sequentially increasing in width. Vacuum to be generated is controlled on the basis of the above distance and the bending angle of the trailing rails.

This is a divisional of application Ser. No. 08/953,647 filed Oct. 17,1997, the disclosure of which is incorporated herein by reference, nowU.S. Pat. No. 5,953,181.

BACKGROUND OF THE INVENTION

The present invention relates to a magnetic disk drive and, moreparticularly, to a flying magnetic head slider capable of recording andreproducing data while flying slightly above a recording medium due toan air bearing.

A magnetic disk drive applicable to a computer as an external storageincludes a magnetic head for recording and reproducing data out of arecording medium. The head is mounted on a magnetic head slider facingthe recording medium and capable of flying to a preselected height abovethe medium. While the medium spins, the resulting viscous flow of air isborn by an air bearing surface facing the medium. The slider thereforeflies slightly above the medium due to an air bearing available with theair bearing surface. The head is mounted on the air outlet end portionof the air bearing surface and oriented toward the medium. During theflight of the slider, the head records or reproduces data in or out ofthe medium without contacting the medium.

The slider of the type described is brought to a desired track by apositioner while seeking the medium. Specifically, with such a rotaryactuator type positioner, to access data, the slider seeks the mediumfrom the innermost circumference to the outermost circumference of thetrack. This brings about a problem that the pressure acting on the airbearing surface depends on the radial position of the track of themedium because the velocity of the viscous flow of air depends on theradial position of the track. As a result, the flying height of theslider differs from one radial position to another radial position ofthe track. Moreover, the yaw angle between the direction tangential tothe medium and the longitudinal axis of the slider differs from theinnermost circumference to the outermost circumference. A change in yawangle causes the air stream flowing along the air bearing surface tovary, thereby varying the pressure distribution. This also causes theflying height of the slider to fluctuate.

A change in the flying height of the slider directly translates into achange in electromagnetic transduction efficiency available with thehead and thereby deteriorates a signal-to-noise ratio. To implement highdensity CDR (Constant Density Recording) required of a magnetic disk, itis necessary to maintain a high BPI (Bit Per Inch) over the entire trackarea. It is therefore extremely important to guarantee the constantflying height of the slider over the entire track area.

Technologies relating to the present invention are also disclosed in,for example, Japanese Patent Laid-Open Publication Nos. 61-160885,3-125378 and 4-228157.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a flyingmagnetic head slider allowing a minimum of change to occur in flyingheight without regard to the radial track position and thereby ensuringa stable flying height over the entire track area.

It is another object of the present invention to provide a flyingmagnetic head slider allowing a minimum of change to occur in recordingand reproducing characteristics and thereby implementing high densityCDR.

In accordance with the present invention, a magnetic head slider havingan air bearing surface and capable of flying due to an air bearingbetween the air bearing surface and a recording medium includes aleading rail formed at an air inlet side on the air bearing surface. Apair of trailing rails extend from substantially the center of theleading rail toward an air outlet, then bend away from each other, andthen respectively extend toward the right end and left end of the airoutlet end while sequentially increasing in width.

Also, in accordance with the present invention, a magnetic head sliderhaving an air bearing surface and capable of flying due to an airbearing between the air bearing surface and a recording medium includesa generally C-shaped leading rail formed at an air inlet end on the airbearing surface and concave toward an air outlet end. A pair of trailingrails extend from substantially the center of the concavity of theleading rail toward the air outlet end, then bend away from each other,and then respectively extend to the right end and left end of the airoutlet end while sequentially increasing in width.

Furthermore, in accordance with the present invention, a magnetic headerslider having an air bearing surface and capable of flying due to an airbearing between the air bearing surface and a recording medium includesan air inlet end and an air outlet end formed by separating the airbearing surface. A generally E-shaped leading rail is formed at the airinlet end and concave toward the air outlet end. A pair of triangulartrailing rails are respectively located at the right end and left end ofthe air outlet end.

Moreover, in accordance with the present invention, a magnetic headslider having an air bearing surface and capable of flying due to an airbearing between the air bearing surface and a recording medium includesan air inlet end and an air outlet end formed by separating the airbearing surface. A generally E-shaped leading rail is concave toward theair outlet end. Three subrails extend toward the air outlet and areseparated from each other by a pair of parallelogrammatic recesses whichare symmetrical to each other with respect to the longitudinal axis ofthe slider. A pair of triangular trailing rails are respectively locatedat the right end and left end of the air outlet end and symmetrical toeach other with respect to the longitudinal axis of said slider.

In addition, in accordance with the present invention, a slider havingan air bearing surface including an air inlet end and an air outlet end,and capable of flying due to an air bearing between the air bearingsurface and a recording medium includes three leading rails respectivelyextending out from the right end, left end and center of the air inletend. A pair of side rails extend toward the air outlet end and arerespectively formed at the right end and left end of the slider. Theside rails each extends while sequentially decreasing in width, andterminates before reaching the air outlet end. A center rail extendsfrom the center of the air inlet end toward the air outlet end and thenbifurcates into a pair of branch rails. The branch rails respectivelyextend to the right end and left end of the air outlet end whilesequentially increasing in width.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other object, features and advantages of the presentinvention will become apparent from the following detailed descriptiontaken with the accompanying drawings in which:

FIGS. 1A and 1B are respectively a plan view and a front view showing aconventional double-rail type magnetic head slider;

FIGS. 2A and 2B are respectively a plan view and a front view showing aconventional double-rail type TPC (Transverse Pressure Contour) magnetichead slider;

FIGS. 3A and 3B are respectively a plan view and a front view showing aconventional triple-rail type magnetic head slider;

FIG. 4 is a perspective view showing a conventional double-rail typemagnetic head slider;

FIG. 5 is a plan view demonstrating how a magnetic head slider accessesa recording medium;

FIG. 6A is a plan view showing a first embodiment of the magnetic headslider in accordance with the present invention;

FIG. 6B is a perspective view of the first embodiment;

FIGS. 7 and 8 are plan views respectively showing a first and a secondmodification of the first embodiment;

FIG. 9A is a plan view showing a second embodiment of the magnetic headslider in accordance with the present invention;

FIG. 9B is a perspective view of the second embodiment;

FIGS. 10-13 are plan views respectively showing a first to a fourthmodification of the second embodiment;

FIG. 14A is a plan view showing a third embodiment of the magnetic headslider in accordance with the present invention;

FIG. 14B is a perspective view of the third embodiment;

FIGS. 15A and 15B are respectively a plan view and a perspective viewshowing a modification of the third embodiment;

FIGS. 16-18 each shows a particular pressure distribution on an airbearing surface included in a magnetic head slider of the presentinvention;

FIG. 19 shows the peripheral speed dependency of a flying heightparticular to the present invention;

FIG. 20 shows the yaw angle dependency of a flying height alsoparticular to the present invention;

FIG. 21 shows the track radius dependency of a flying height alsoparticular to the present invention; and

FIGS. 22A-22C each shows a specific relation between the rail geometryof a magnetic head slider and the yaw angle achievable with the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

To better understand the present invention, brief reference will be madeto conventional flying magnetic head sliders, shown in FIGS. 1A, 1B, 2A,2B, 3A and 3B. FIGS. 1A and 1B show a double-rail magnetic head slider10 having two parallel rails or side rails arranged at both sides of anair bearing surface. FIGS. 2A and 2B show a TPC magnetic head slider 20having two parallel side rails 22. In this head slider 20, each siderail 22 has a finely stepped configuration in order to generate vacuum.FIGS. 3A and 3B show a triple-rail magnetic head slider 30 having a pairof side rails 32 arranged at both sides of an air bearing surface, and asingle center rail 34 intervening between the side rails 32. Among suchconventional sliders, the head slider shown in FIGS. 1A and 1B will bedescribed more specifically hereinafter.

As shown in FIG. 4, the slider 10 has a recess 13 formed in the side ofthe slider 10 facing a recording medium, not shown. The recess 13 has apreselected width and extends throughout the slider 10 in the lengthwisedirection of the slider 10, forming the air bearing surface 11. Theparallel side rails 12 are arranged at both sides of the recess 13 andextend in the direction (arrow e) in which air flows due to the spinningof the recording medium. The rails 12 each has a tapered end at the airinlet side 14 of the head 10. A record/reproduce head 17 is mounted onthe other end of one of the rails 12 at the air outlet side 16 of thehead 10. In operation, air flows along the side rails 12 via the taperedends 15 due to the rotation of the medium, forming an air film betweenthe head 10 and the medium. As a result, the slider 10 is caused to flyabove the medium.

FIG. 5 shows the locus of the above head slider 10 carried on a rotaryactuator type positioner 18. As shown, the slider 10 is caused to seeksa recording medium 19 by the positioner 18 and is positioned above adesired track. Specifically, the positioner 18 carrying the slider 10 onits one end is rotated about the other end along the surface of themedium 1, as indicated by an arrow f in FIG. 5. To access data, theslider 10 with the head 17 seeks the medium 19 from the innermostcircumference A to the outermost circumference B of the track.

The problem with the slider 10 is that the pressure acting on the airbearing surface 11 depends on the radial position of the track of themedium 19 because the velocity of the viscous flow of air depends on theradial position of the track. As a result, the flying height of theslider 10 differs from one radial position to another radial position ofthe track, as discussed earlier. Moreover, the yaw angle between thedirection tangential to the medium 19 and the longitudinal axis of theslider 10 differs from the innermost circumference (θ_(in)) to theoutermost circumference (θ_(out)). A change in Yaw angle causes the airstream flowing along the air bearing surface 11 to vary, thereby varyingthe pressure distribution. This also causes the lying height of theslider 10 to vary.

Preferred embodiments of the magnetic head slider in accordance with thepresent invention will be described hereinafter.

1st Embodiment

FIGS. 6A and 6B show a magnetic head slider embodying the presentinvention while FIGS. 7 and 8 respectively show a first and a secondmodification of the embodiment. There are shown in FIGS. 6A, 6B, 7 and 8magnetic head sliders 101-103, air bearing surfaces 201-203, leadingrails 301-303, trailing rails 401-403, a center rail 501, a trailingsubrail 601, a magnetic head 17, tapered portions 801-803, and recesses901-903. The sliders 101-103 each is connected to a head supportmechanism, not shown, at its side opposite to the air bearing surface201, 202 or 203.

As shown in FIGS. 6A and 6B, the leading rail 301 is positioned at theleading edge side of the slider 101 and provided with a generallyC-shaped configuration concave toward the trailing edge of the slider101. The trailing rail 401 extends from substantially the center of theconcavity of the C-shaped configuration of the leading rail 301 whileflaring generally in the form of a letter V. With an increase in theextension of the right and left ends of the leading rail 301 toward thetrailing edge, the roll rigidity and the enclosing area of the reversestep surface increase, intensifying the vacuum. However, excessiveextension would cause air to stagnate in the portions of the recess 901between the right and left ends of the leading rail 301 and the flaredtrailing rail 401. In light of this, the right and left ends of theleading rail 301 should preferably be tapered toward the right and leftends of the slider 101.

The two portions of the flared trailing rail 401 (subrails hereinafter)are spaced from each other by a distance h1 in the vicinity of theleading rail 301. The two subrails are bent at an angle θ_(t1) away fromeach other while extending toward the trailing edge. Then, the subrailsterminate at the trailing edge while sequentially increasing theirwidth. Vacuum is controllable on the basis of the above distance h1 andangle θ_(t1). Specifically, vacuum will be intensified if the distanceh1 and angle θ_(t1) are increased. However, when either one of thedistance h1 and angle θ_(t1) is increased, the other cannot beincreased. Ideally, the angle θ_(t1) should lie in the same range as theexpected yaw angle in order to guarantee a desirable yaw anglecharacteristic. The distance h1 should preferably be selected on thebasis of such an angle θ_(t1).

As shown in FIG. 7, the magnetic head slider 102 representative of thefirst modification is applied to a triple-pad type slider. As shown, theleading rail 302 is substantially identical in configuration with theleading rail 301 shown in FIGS. 6A and 6B. The trailing rail 402extending from the leading rail 302 is similar to the trailing rail 401shown in FIGS. 6A and 6B except for the following. The two subrails ofthe trailing rail 402 are spaced by a distance h2 and bent away fromeach other at an angle θ_(t2). Although the subrails of the trailingrail 402 extend toward the trailing edge as in the illustrativeembodiment, they respectively terminate at the right and left ends ofthe slider 102 before reaching the trailing edge.

The subrails of the trailing rail 402 should have a length L preferablygreat enough to prevent the slider 102 from contacting a recordingmedium, not shown, at the maximum roll position of the slider 102. Thecenter rail 501 is positioned at the center of the trailing edge andprovided with an equilateral triangular configuration or a polygonalisland-like configuration. The head 17 is mounted on the center rail501. Preferably, the center rail 501 should be as close to a regularpolygon as possible in order to reduce the variation of the pressuredistribution ascribable to the variation of the yaw angle.

The above modification allows the distance h2 and angle θ_(r2) to begreater than he distance h1 and angle θ_(t1) of the embodiment. Theslider 102 can therefore be so designed as to further reduce theperipheral speed dependency and yaw angle dependency of the flyingheight.

The magnetic head slider 103 shown in FIG. 8 and representative of thesecond modification enhances the free setting of the distance h1 andangle θ_(t1) of the illustrative embodiment and thereby further improvesthe peripheral speed characteristic and taw angle characteristic. Asshown, the two subrails of the trailing rail 403 extending from theleading edge terminate halfway while the trailing subrail 601 extendfrom the trailing edge toward the trailing edge, as illustrated.

The subrails of the trailing rail 403 and the trailing subrails 601 arebent at angles θ_(t3) and θ_(t4), respectively. The angle θ_(t3) shouldpreferably be smaller than the angle θ_(t4) in order to improve both theperipheral speed dependency and yaw angle dependency. Particularly, withthis modification, both the peripheral speed dependency and yaw angledependency can be improved with desirable balance because vacuum and yawangle characteristic can be designed independently of each other to somedegree due to the separate configuration of the leading rail 403.

As stated above, in the illustrative embodiment and its modifications,the C-shaped leading rail located at the leading edge of the air bearingsurface defines a reverse step surface with its concavity. The right andleft ends of the leading rail and the flared trailing rail extendingfrom the center of the leading rail divide the reverse step surface intothree portions. These three portions are respectively enclosed by theend portions of the leading rail and the trailing rail. FIGS. 16-18 showvacuum generated in each of the three enclosed portions of the reversestep surface. The negative load capacity (vacuum intensity Wn) increaseswith an increase in the velocity of the viscous flow of air and cancelsthe positive load capacity (flying force Wp). Therefore, the peripheralspeed dependency of the flying height can be reduced so as to improvethe uniformness of the flying height.

To ensure the reliability of a disk drive, it is necessary to improvethe flying characteristic and lower CSS durability. For this purpose,the pressure load must be reduced in order to reduce the wear betweenthe slider and the medium and the resistance to the flight at the timeof start-up. However, with the conventional positive pressure sliders, adecrease in pressure load is apt to deteriorate air film rigidity andtherefore tracking ability.

By contrast, with the vacuum type slider, a great positive load capacityis achievable despite the light load and guarantees sufficient air filmrigidity. On the other hand, as shown in FIG. 22A, the generallyV-shaped trailing rail has its two subrails inclined at an angle of ±θt.Therefore, even when the yaw angle θ_(Y) of the slider varies due to achange in track position, the air stream coming in through the leadingedge reaches the trailing edge more easily and does not noticeably varythe flow rate of air bearing. This allows the yaw angle dependency ofthe flying height to be reduced, and therefore ensures stable flight atthe time of seek. This, coupled with the reduced peripheral speeddependency, realizes constant flight over the entire track area.

2nd Embodiment

FIGS. 9A and 9B show a second embodiment of the present invention whileFIGS. 10-13 respectively show a first to a fourth modification of thesecond embodiment. There are shown in FIGS. 9A, 9B and 10-13 magnetichead sliders 104-108, air bearing surfaces 204-208, leading rails304-308, trailing rails 404-407, a center rail 502, the magnetic head17, tapered portions 804-808, and recesses 904-908. The sliders 104-108each is connected to a head support mechanism, not shown, at its sideopposite to the air bearing surface 204, 205, 206, 207 or 208.

As shown in FIGS. 9A and 9B, the head slider 104 has the leading rail304 extending from the leading edge toward the trailing edge generallyin the form of a letter E. The two concavities or recesses of theE-shaped leading rail 304 are implemented as a pair of parallelogramssymmetrical to each other with respect to the lengthwise axis of theslider 104. The above concavities form a generally V-shaped recess, asseen from the leading edge side. The angle of “V” of such a recessshould preferably be great enough to prevent dust from staying in therecess. Although an increase in the area of the V-shaped recessintensifies vacuum, it reduces the rail area for generating a positivepressure. As a result, the roll and pitch rigidity decrease, and theflying height decreases to decrease the flying pitch angle.

The trailing rail 404 is implemented by a pair of triangular railsextending from the right and left ends of the trailing edge. Thetriangular rails are symmetrical to each other with respect to thelongitudinal axis of the slider 104 and are flared away from each other,as seen from the leading edge side.

The trailing rails 404 each is inclined by an angle of θ_(E13) relativeto the longitudinal axis of the slider 104. The right and left railsincluded in the leading rail 304 each is inclined by an angle of θ_(E11)relative to the above axis while the center rail is inclined by an angleθ_(E12). These angles θ_(E11)-θ_(E13) should preferably by equal to orgreater than the expected yaw angle.

As shown in FIG. 10, in the slider 105 representative of the firstmodification, the leading rail 305 is similar in configuration to theleading rail 304 of the embodiment except that it forms a generallyV-shaped recess, as seen from the trailing edge side. Again, the angleof “V” should preferable be great enough to prevent dust from staying inthe recess. The trailing rails 405 are similar to the trailing rails 404of the embodiment except that they are flared, as seen from the trailingedge side.

The trailing rails 405 each is inclined by an angle of θ_(E23) relativeto the longitudinal axis of the slider 105. The right and left railsincluded in the leading rail 305 each is inclined by an angle of θ_(E21)relative to the above axis while the center rail is inclined by an angleof θ_(E22). These angles θ_(E21)-θ_(E23) should preferably be equal toor greater than the expected yaw angle.

As shown in FIG. 11, in the slider 106 representative of the secondmodification, the leading rail 306 is identical in configuration withthe leading rail 304 of the embodiment. The trailing rails 406 areidentical in configuration with the trailing rails 405 of the firstmodification. The head slider 106 is desirable when in the secondembodiment roll rigidity should be increased, and pitch angle should bereduced.

As shown in FIG. 12, in the slider 107 representative of the thirdmodification, the leading rail 307 is identical in configuration withthe leading rail 305 of the first modification. The trailing rails 407are identical with the trailing rails 404 of the second embodiment. Thehead slider 107 is desirable when in the first modification rollrigidity should be increased, and pitch angle should be reduced.

Further, as shown in FIG. 13, in the slider 108 representative of thethird modification, the leading rail 308 is similar to the leading rail304 of the second embodiment. The center rail 502 is implemented as anequilateral triangle or a polygon and located at the center of thetrailing edge. The center rail 502 should be as close to a regularpolygon as possible so as to reduce the influence of the air bearingcondition susceptible to a change in yaw angle, thereby reducing the yawangle dependency. The trailing rail 502 is usable when any one of thesecond embodiment and its modifications is provided with a geometryadaptive to a triple-pad type slider.

As stated above, in the second embodiment and its modifications, theleading rail is provided at the leading edge of the air bearing surfacefacing a recording medium. The leading rail is implemented in the formof a letter E concave toward the tailing edge. The leading edge includesa tapered portion. Three portions, or subrails, of the E-shaped leadingrail extending toward the trailing edge are separated from each other bya pair of parallelogrammatic recesses symmetrical to each other withrespect to the longitudinal axis of the slider. A pair of triangularrails implement the trailing rail and are symmetrical to each other withrespect to the longitudinal axis of the slider, or a single polygonalrail is located at the center of the trailing edge.

The E-shaped leading rail located at the leading edge of the air bearingsurface defines a reverse step surface with its pair ofparallelogrammatic recesses enclosed by three subrails. Vacuum isgenerated in the two enclosed regions and cancels the positive loadcapacity (flying force) ascribable to an increase in the air flow rate.Therefore, the peripheral speed dependency of the flying height can bereduced. At the same time, the flying characteristic and CSS durabilitycan be enhanced to guarantee the reliability of a disk drive.

Further, the pair of parallelogrammatic recesses symmetrical to eachother with respect to the longitudinal axis of the slider set up apressure distribution increasing at both sides of the leading rail. Thissuccessfully improves roll ridigity.

Assume the trailing rail implemented by the pair of trianglessymmetrical to each other with respect to the longitudinal axis of theslider. Then, as shown, in FIG. 22B, even when the yaw angle (θ_(Y)) ofthe slider varies, the two triangles do not noticeably vary the airbearing amount in combination with the three subrails of the leadingrail which are inclined by angles of θ₁-θ₃. If follows that the yawangle dependency of the flying height can be reduced to implement stableflight at the time of seek. This, coupled with the reduced peripheralspeed dependency stated earlier, guarantees a constant flying heightover the entire track area.

3rd Embodiment

FIGS. 14A and 14B show a third embodiment of the present invention whileFIGS. 15A and 15B show a modification thereof. There are shown in FIGS.14A, 14B, 15A and 15B magnetic head sliders 109 and 110, air bearingsurfaces 209 and 210, center rails 503 and 504, side rails 1001 and1002, the magnetic head 17, tapered portions 809 and 810, recesses 909and 910, and a machined groove 1003. The sliders 109-110 each issupported by a magnetic head support mechanism on its side opposite tothe air bearing surface 209 or 210.

As shown in FIGS. 14A and 14B, the side rails 1001 each extends from theright end or the left end of the leading edge toward the trailing edge,sequentially decreases in width toward the right end or the left end ofthe slider 109 from around the center of gravity of the slider 109, andterminates before reaching the trailing edge. The center rail 503extends from the leading edge toward the trailing edge with a smallwidth, and bifurcates into branch rails 503-R and 503-L at the positionwhere the side rails 1001 begin to decrease in width. The branch rails503-R and 503-L respectively extend to the right and left ends of thetrailing edge. Thus, the center rail 503 is generally Y-shaped, as seenfrom the leading edge side.

The gaps between the side rails 1001 and center rail 503 shouldpreferably be broad enough to prevent dust from accumulating. To reducethe yaw angle dependently, angles θ_(c1) and θ_(c2) between the branchrails 503-R and 503-L and the longitudinal axis of the slider shouldpreferably be equal to or greater than the expected yaw angle.

As shown in FIGS. 15A and 15B, the slider 110 representative of themodification of the third embodiment is desirable when the recess of thethird embodiment cannot be deep due to machining limitations. As shown,the machined groove 1003 is formed between the side rails 1002 and thecenter rail 504, so that the flying height can be prevented fromincreasing due to a shallow recess. In this case, the center rail 504 isgenerally V-shaped, as seen from the leading edge side.

As stated above, in the third embodiment and its modification, a pair ofside rails are provided at the right and left ends of the leading edgeof the air bearing surface while a single center rail is located at thecenter of the trailing edge. The side rails each extends toward thetrailing edge, sequentially decreases in width, and terminates beforereaching the trailing edge. The center rail extends linearly from theleading edge toward the trailing edge and then bifurcates. Thebifurcated portions or branch rails extend away from each other to theright and left ends of the trailing edge while sequentially increasingin width.

In the above configuration, a reverse step surface is formed from thebifurcating point of the center rail toward the trailing edge, causingvacuum to be generated in the area enclosed by the branch rails. Thissuccessfully reduces the peripheral speed dependency of the flyingheight, as stated earlier, and in addition implements a sufficienteffective load (positive load capacity) and sufficient air film rigiditydespite a light load.

As shown in FIG. 22C, the branch rails flared toward the trailing edgeeach is inclined by an angle of ±θb relative to the longitudinal axis ofthe slider. Therefore, even when the yaw angle of the slider varies dueto a change in track position, the air stream coming in through theleading edge reaches the trailing edges (air outlet ends) of the branchrails more easily, preventing the air bearing amount from noticeablyvarying. It follows that a change in flying height ascribable to achange in yaw angle can be reduced so as to ensure stable flight at thetime of seek. This, coupled with the reduced peripheral speed dependencystated earlier, guarantees uniform flight over the entire track area.

FIGS. 18 and 20 compare the present invention and the conventionaltechnologies with respect to a relation between the variation ofperipheral speed and the flying height and a relation between thevariation of yaw angle and the flying height. In accordance with thepresent invention, the peripheral speed dependency and yaw angledependency of the flying height are less noticeable than those of theconventional technologies. Therefore, as shown in FIG. 21, the presentinvention is capable of reducing the variation of the flying heightdependent on the radial position of the track With the presentinvention, it is possible to realize a constant flying height which isthe key to high density recording.

The conventional double-rail type TPC slider is comparable with thepresent invention as to the constant flying height. However, this typeof conventional slider achieves a constant flying height by causing thevariation of the flying height ascribable to the varying peripheralspeed and the variation of the flying height ascribable to the varyingyaw angle to cancel each other. Therefore, in the conventional slider,the flying height is greatly dependent on the peripheral speed and yawangle, obstructing stable flight at the time of high speed seek. As aresult, a disk drive with such a slider lacks in reliability in the lowheight region where a sufficient margin is not available as to theflight.

In summary, in accordance with the present invention, a magnetic headslider generates vacuum on a reverse step surface implemented by an airbearing surface. A rail forming the reverse step surface is soconfigured as to reduce the variation of a pressure profile ascribableto a yaw angle. The slider therefore reduces both the peripheral speeddependency and yaw angle dependency of the flying height of a magnetichead at the same time. It follows that the flying height of the head isconstant over the entire track area, and stable flight is ensured duringhigh speed seek even when a margin as to the low flying height islimited. This, coupled with the fact that the pressure load to act onthe slider can be reduced at the design stage, reduces CSS wear andimproves the flying characteristic and thereby enhances the reliabilityof a disk drive.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof.

What is claimed is:
 1. A magnetic head slider having an air bearingsurface and capable of flying due to an air bearing between said airbearing surface and a recording medium, said slider comprising: agenerally E-shaped leading rail formed at an air inlet end of said airbearing surface, said leading rail being unitary and having threesubrails extending generally toward an air outlet end of said airbearing surface and forming said E-shape; and a pair of triangulartrailing rails respectively located at a right end and a left end ofsaid air outlet end.
 2. A slider as claimed in claim 1, wherein saidtrailing rails are separate from said leading rail.
 3. A magnetic headslider having an air bearing surface and capable of flying due to an airbearing between said air bearing surface and a recording medium, saidslider comprising: a generally E-shaped leading rail formed at an airinlet end of said air bearing surface, said leading rail being unitaryand having three subrails extending toward an air outlet end of said airbearing surface and forming said E-shape, said subrails being separatedfrom each other by a pair of parallelogrammatic recesses which aresymmetrical to each other with respect to a longitudinal axis of saidslider; and a pair of triangular trailing rails respectively located ata right end and a left end of said air outlet end and symmetrical toeach other with respect to the longitudinal axis of said slider.
 4. Aslider as claimed in claim 3, wherein said E-shaped leading rail isconfigured such that said pair of recesses generally form a letter V, asseen from said air outlet side.
 5. A slider as claimed in claim 4,wherein said pair of trailing rails each increases in width from a sideof said slider toward said air outlet end.
 6. A slider as claimed inclaim 3, wherein said trailing rails are separate from said leadingrail.
 7. A slider as claimed in claim 3, wherein said E-shaped leadingrail is configured such that said pair of recesses generally form aletter V, as seen from said air inlet side.
 8. A slider as claimed inclaim 7, wherein said pair of trailing rails each increases in widthfrom a side of said slider toward said air outlet end.
 9. A magnetichead slider heaving an air bearing surface and capable of flying due toan air bearing between said air bearing surface and a recording medium,said slider comprising: a generally E-shaped leading rail formed at anair inlet end of said air bearing surface, said leading rail havingthree subrails extending generally toward an air outlet end of said airbearing surface and forming said E-shape; and a pair of triangulartrailing rails respectively located at a right end and a left end ofsaid air outlet end, wherein said trailing rails are separate from saidleading rail.
 10. A magnetic head slider having an air bearing surfaceand capable of flying due to an air bearing between said air bearingsurface and a recording medium, said slider comprising: a generallyE-shaped leading rail formed at an air inlet end of said air bearingsurface, said leading rail having three subrails extending toward an airoutlet end of said air bearing surface and forming said E-shape, saidsubrails being separated from each other by a pair of parallelogrammaticrecesses which are symmetrical to each other with respect to alongitudinal axis of said slider; and a pair of triangular trailingrails respectively located at a right end and a left end of said airoutlet end and symmetrical to each other with respect to thelongitudinal axis of said slider, wherein said trailing rails areseparate from said leading rail.